Dip terminal for testing wires



A. J. scHULTz 2,740,099

DIP TERMINAL FOR TESTING WIRES March 27, 1956 Filed June 30, 1952 F/aa F/Gz @P777/J1? J SCHUL 72 CW @M 22. me

United States Patent() 2.7495929 DIP TERMINAL Fomrns'rlNG WIRES Arthur Joseph 1nd. Applications@ 30,495.2, sensi No. 196,505

scusarmi (Granted under Title 35, U.S.'Code (1952), sec. 266) The invention .described .herein may be .manufactured and used by or for theGovernmen't .of the United States of America for governmental'lprposes without the paymcntof any royalties thereonor therefor.

This invention relatcsncrlllly to testingterminals, .and more particularly ,toa transparent terminal ,embodying mercury asa huid .electrical contact medium.

The purpose of-.this invention is to provide a terminal means for expedientlyfrepeating a multiplicity of electrical connections during tlieprog'ress of testing, altering, modifying or matching a particular.electrical.component, such as a Awire coil, to 'a,presnelectled .electrical value.

Electrical components, suchQas coils, must be manufactured to have a predetermined design value of inductance, flux, reactance, phase shift, etc. In the manufacturing process this design valueisarrivedatby cutting off portions of the coil wire untilthe component on test affects its design value. In the case of v'ery" tlne coated wire, such as No. 22 AWG or liner, the' repeated shortening, for the purpose of arriving at the preselected value, results in a tcdiousand time consuming series of operations especially in so far as the preparation of the wire for connection into the test circuit is concerned.

This invention provides a new way of handling this very fine coated wireduringthe-testing operation. 'Such a very tine wireisusuallycovered witha varnish-hkcinsulating coating ,which-,heretofore needed to be removed before connecting to a conventional post. This removal of the insulation is' vrieti a time consuming operation but is also a dangerous andda'ma'gin'g operation. The old method of performing the function of this invention was to remove the varnish-like insulating coating from the wire around a conventional terminal post to complete the circuit. Burning ot! the varnish-like insulation by means of a ame creates a lire hazard to the environs as well as a personal danger to the individual operator inadvertently reaching over the flame. Sandpapering the end of a very fine wire, auch as No. 22 AWG or finer, is a very difficult operation because of its very small diametral dimension, and is otherwise inadequate for a clean removal job. Scraping the end of a very line wire, such as No. 22 AWG or liner, with a knife edge is unsatisfactory because of the great possibility of cutting too deeply and developing weak points, particulnrly where the knife edge first bears down on the tine wire, thereby inducing breakage of the wire when it is wound around the te An object of this invention is to provide terminal means that allow a testing operator to make repeated electrical connections thereby without the necessity of preparing the wire for connection into a circuit.

Another object of this invention is to provide terminal means that eliminate the annoying openden ot winding a fine wire around a terminal post.

A further object of this invention is to provide terminal means that allows tthe making of a multiplicity of repeating electrical connections with great expediency.

Yet another object of this invention is to provide ter- 2,740,099 :Patented Mar. 27, 1956 minal means whose electrical contact characteristics are at an optimum.

A still further object of this invention is to provide transparent dip terminal meansthat allows an'observer witness the penetration of an..electricallead into a liutd contact medium therein, .thereby assuring electrical con-4v Fig. l shows a perspective view of a preferred embodiment of the invention.

Fig. 2 illustrates alongitudinal sectional view throughv the device, showing. themercury receiving chambers.

Fig. 3 is a cross-.section view of the device, showing one of the mercury k,receiving chambers.

Referring now to the drawings, wherein like reference numerals designate/like or corresponding parts throughout the several views, thereis shown a block or body portion 10 having 'a cover portion 11. At the extreme ends of the blockportion are provided bores 12 .and.`. 13, respectively, adapted to receive mounting bolts (not shown). The upper endsof said vbores are counterbored as at 14 and 15 to receivesaid bolt heads therein, vso as not to interfere with .the fitting of .the cover on vthe body.

Between said mounting bolt' bores are 4provided recesses i6 and 17 for the containing of a non-wetting fluid .electrical conductingrnediutn, such as mercury 18 and 19,

or the like, therein.

A plurality of threaded bores 21, 22 and.23, are provided in said body member to receivescrews 24, 25 and 26, respectively, for securing .the cover I11 to the body 10. 'Said cover is provided with countersunkvbores, in registry Vwith the .thread'ed'body .bores 21, 22 -and 23, .to receive the screws. 24, '25 .and '2.6, therethrough.

A pair of funnel-lilte apertures, .or countersunk bores,

' 27 and-28, are alsoprovideil'inthecover, disposed to communicate wilthbody' recessesdtiand.17,.respectvely. The countersunk portions '32"ar'id 33 of a substantial diameter so as to function as a guido to conveniently direct the testing leads to the small tubular portions 27 and 28 of the funnel, and thence into the mercury.

The bores 27 and 28, in this the preferred construction, are of a very small diameter, such as to receive a No. 22 AWG wire or finer. In the event the dip terminal device, having mercury therein, should overturn, the mercury therein will not escape through the bore 32 and 33 because the capillary force due to the surface tension is greater than all the other forces tending to force the mercury out through the bore. In its broadest conception then, for any particular non-wetting conducting iiud medium used, the diameter of the bore, for a spill-proofdcsign, shall be sufficiently small so that the sum of the forces tending to project the fluid from the tube is less than the capillary force resulting from surface tension tending to hold the liquid in the bore.

The body and cover portions are preferably made' of a transparent material such as glass, Plexiglass, Lucite, or the like, to permit the observation of a wire being thrust into the mercury. However, metals, such as stainless steel, that do not contaminate the mercury with metallic oxides and other foreign matter, may also be used.

Electrical connecting bars 29 and 31 are provided extending through the front wail of the Lucite body, and through the mercury bath, and into the rear wall of the body. The bars are snuglyiit in receiving bores to prevent leakage of mercury.

Operation: In repetitious -testing operations where repeated electrical connections are necessary to be made such as in impedance matching of coils, a portion of the wire coil will necessarily have to be progressively removed. With the subject dip terminal at hand, the operable end of the coated coil is merely cut with a snipper, exposing a freshly cut cross-sectional face of the coil end. The wire end, with its insulation coating untouched, is then expediently directed into the funnel tube, guided by the conical funnel-like walls, and thence into the mercury. The penetration of the wire into the mercury can be witnessed by observation through the transparent nature of the subject dip terminal.

After repeated shortenings of'the coil, an indicating instrument in the test circuit (not shown) will indicate the desired impedance value. The test coil is then withdrawn from the mercury and detached from the test circuit. Another untested component is then inserted in the test circuit and the operation repeated.

The features characterizing this dip terminal are the provision of plastic body and cover which will not contaminate mercury, thereby always maintaining a low electrical resistance mercury surface; the provision of funnel-like guide means to expediently guide a wire end into the mercury chamber; a transparent structure to permit the observation of a wire being thrust into the contact mercury; the provision of an apertured cover for removably retaining a wire in a terminal during testing operations; and the embodiment of a fluid contact medium which readily flows against the fresh cross-sectional cut face of a wire without necessitating the removal of the insulation from the periphery of the wire as in the conventional method of terminal connections.

It'should be understood, of cours'e,''t1ia't' the foregoingdisclosure relates to' only a preferred embodiment of theinvention and that numerous modifications or alterations may'be made therein without departing from the spirit and the scope of the, invention.

AWhat is claimed and"desired to be` protected by Letters Patent of the vUnited' States is:

1. A dip'terminal, comprising: a body member having a recess for the containment of a fluid therein; a wetting resistant liquid electrical conducting mediumv having a high vsurface tensionin said recess; a cover over /said recess secured to `said body, said cover being apertured by a countersunk aperture'to communicate with said recess, said aperture being of a dimensional measure so that when said body member is inverted the sum of all forces tending to project said liquid through said aperture is less than the capillary force resulting from the' surface tension tending to hold the liquid in said aperture; and one terminal means electrically connected with said conducting liquid through said body member.

2. A dip terminal, comprising: a body member having a recess for the containment of a fluid therein; mercury in said recess; a-cover having an aperture therein over said recess, said cover being secured to said body, said cover aperture being countersunk at the top end and of a dimensional measure so that -when said body member is inverted the sum of all forces tending to project said mercury through said aperture is less than the capillary force resulting from the surface tension tendingA to hold said mercury in said aperture; and one terminal means electrically connected with said mercury through said body member. l

3. A dip terminal; comprising:'a transparent block body' member having at least one recess therein for the containment ofl auid; mercury in said recess; a transparent cover over 'said' recess removably secured to said body,v said cover'being -apertured to communicate with said recess, and said aperture "being countersunk at the top end thereof andI of a dimensional measure so that when said body is inverted the sum of all forces tending to project said mercury through said aperture is less than the capillary force resulting from the surface tension tcndingto hold the mercury in said aperture; and a terminal har meanspa'ssing through the body member wall and into contact with saidmercury.

References Cited inthe le of this patent UNITED STA'1 `ES PATENTS OTHER REFERENCES Hyde, abstractofapplication 206,902 published May 20, 1952,(aba11d0nd), 65,8 O. G. 918. 339-118. 

